#include<bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=a;i<b;i++)





int N, P;
#define INF INT_MAX/2
int dp[2][201010];
//-----------------------------------------------------------------
int main() {
	cin >> N >> P;

	rep(i, 0, 2) rep(j, 0, 201010) dp[i][j] = INF;
	dp[0][0] = 0;

	rep(_i, 0, N) {
		int i = _i % 2;
		int ii = (_i + 1) % 2;

		rep(j, 0, 201010) dp[ii][j] = INF;

		int a, b, c;
		scanf("%d%d%d", &a, &b, &c);

		rep(j, 0, P + 1) if (dp[i][j] != INF) {
			dp[ii][j + 3] = min(dp[ii][j + 3], dp[i][j] + 1);
			dp[ii][j + 2] = min(dp[ii][j + 2], dp[i][j] + c);
			dp[ii][j + 1] = min(dp[ii][j + 1], dp[i][j] + b);
			dp[ii][j] = min(dp[ii][j], dp[i][j] + a);
		}
	}

	double ans = 1.0 * dp[N % 2][P] / N;
	printf("%.10f\n", ans);
}